1. Field of the Invention
The present invention relates to a lens system, and more particularly, to a lens system in which movable optical members of an optical system in a lens apparatus, such as a focusing member, a zooming member, and a stop, are driven and controlled by an operating unit connected to the lens apparatus as an external apparatus via wireless communication, and an image pickup system including the lens system.
2. Description of the Related Art
A portable electronic news gathering (ENG) camera or a portable camcorder has been known as a television camera for broadcasting or professional use. Sometimes such a television camera is used in a state of being fixed to a mount such as a tripod, a pedestal dolly, or a crane (hereinafter referred to as a “tripod”) and other times in a state of being directly carried by a camera operator on a shoulder or in hand. When the television camera is used in the state of being fixed to the tripod, a controller is often used, which is represented by a demand for remote control. For example, a controller such as a focusing demand or a zooming demand is attached to an end portion of a pan/tilt stick extended from the tripod, and the controller is electrically connected to a lens apparatus mounted on a camera main body with a cable. This enables the camera operator to perform an operation of the controller as well as an operation of pan and tilt of the television camera by using the pan/tilt stick, thus performing a lens operation such as focusing and zooming of the optical system in the lens apparatus by the operation of the controller. The lens apparatus and the controller are connected to each other with a multicore cable, and when further connecting multiple command apparatus, it is necessary to provide as many cables as the number of command apparatus. Therefore, in order to remove the burden of connecting, installing, and disconnecting the cables, an apparatus employing a method of electrically connecting the lens apparatus and the controller so that a signal can be transmitted therebetween without using a cable has been proposed.
For example, in Japanese Patent Application Laid-Open No. 2007-293070, an apparatus is disclosed in which a signal conversion unit is connected to each of a lens apparatus and a demand so that a command signal to be transmitted is converted into a signal supported in wireless communication by the signal conversion unit. The apparatus transmits the command signal and operates the lens apparatus via a wireless connection.
In the conventional technology disclosed in Japanese Patent Application Laid-Open No. 2007-293070 described above, the lens apparatus is configured to be operated by connecting a digital-type demand and transmitting and receiving a digital communication command signal.
However, there is no description on communication speeds between the demand and the signal conversion unit and between the signal conversion unit and the lens apparatus and a communication speed of the wireless communication between the signal conversion units.
When the signal conversion unit such as a wireless unit is interposed in a demand serial communication system between the demand and the lens apparatus, a demand communication rate may become larger than a wireless transmission rate depending on a condition. In this case, a communication speed and a communication data amount cannot be maintained as those before the case happened in contrast to the case of a direct wired connection, which may cause a problem of delay or stagnation of a response to a driving operation.